The oral flora associated with the periodontium is complex and highly variable. Currently, over 264 morphologically distinct bacterial groups have been found within the oral cavity. The role of bacterial plaque in the initiation of periodontal disease as well as changes in the microbial flora during the progressive disease have been well documented. However, the "specific microbial fingerprint" of many periodontal disease processes is yet to be determined. This "fingerprint" is a necessary pre-requisite to defining disease activity on the basis of bacterial morphotypes. Standard techniques of microbiology (culturing and microscopic examination) have obvious limitations. This pilot project is directed towards exploring the possibility of using recombinant DNA techniques coupled to blot hybridizations for a DNA analysis to specific microorganisms associated with periodontal disease. We propose to isolate a DNA specific probe for Wolinella recta (our "prototype" bacterium) and use that probe for determining the presence of this organism in samples isolated directly from the crevice of both healthy and disease periodontiums. It is believed that through careful standarization of the technique and use of appropriate controls this technique can be extended to give reasonable direct estimates of the presence and quantity of specific microorganisms in a particular site.